There are various applications in which one or more components can be exposed to high temperature flow conditions. For instance, many of the components in the combustor section of a turbine engine operate in such an environment. Such components can include head end plates, which are used to close off the combustor chamber, and can further be used to help centralize and align adjacent burners. An example of a head end plate 50 is shown in FIG. 3. Often, a plurality of head end plates 50 are aligned, radially or laterally, side-by-side along the combustor ring 56 as shown in FIG. 4.
Usually, such components contain internal cavities or passages through which a coolant can pass to provide relief from the extremely hot temperatures on the outside. Further, these components may also include sundry coatings to provide additional heat resistance. Despite these measures, there are two recurring problems associated with head end plates. One problem is that of low flow or stagnation zones substantially proximate to the head end plate. The other problem is that of superheated fluids, such as combustion gases, lingering near the head end plates and other components; prolonged exposure to these gases can result in part failure due to high thermal loads, especially at the corners and edges of these components which can act as heat sinks.
There are known methods for minimizing stagnation zones around adjacent components. One general example of such an arrangement is shown in FIG. 1. In this example, a plurality of components 10 having sharp edges and/or corners, such as substantially 90 degree edges 12, are positioned substantially adjacent to each other such that the sharp edges 12 of each component 10 are substantially opposite and parallel to each other. While minimizing the likelihood of stagnation, the components 10 are nevertheless subjected to the high temperatures of combustion, and such a configuration can still result in unacceptably high thermal loads.
As will be described below, the edges and the corners 12 shown in FIG. 1 constitute relatively thicker portions of the component 10. Referring to FIG. 2, assuming the side walls 14 of the component 10 have a substantially uniform thickness x and that the side walls meet at substantially right angles to form an edge 12, then the thickness of the edge would be about x√{square root over (2)}. If three side walls of a component with a thickness x meet at substantially right angles to each other then a corner is formed with a thickness of about x√{square root over (3)}. Thus, the corner and edge portions 12 are relatively thicker than the side walls 14 extending away from the corner and edge portions 12. In these areas of greater thickness, convective heat transfer occurs more slowly between coolant supplied to the interior 13 of the component 10 and the superheated gases impinging on the exterior 15 of the component 10. Consequently, the corners and/or edges 12 act somewhat like heat sinks and become a potential failure point for the component 10.
Numerous configurations, as shown in FIGS. 5A–5D, have been advanced to address the problems of flow stagnation or hot spots at the corners and edges of the components. Referring to FIG. 5A, one design includes two or more components 18 having curved edges/corners 20 such that a constant wall thickness is maintained. This design suffers from the disadvantage that it does not eliminate or reduce the stagnation zone. One improvement is shown in FIG. 5B. This configuration still includes curved edges 22 but now holes 24 are provided in the corners or edges 22 to allow a portion of the internal cooling air to leak into the stagnant flow zone. While such a design helps in minimizing the stagnation zone proximate to the component, it is not always desirable to bleed cooling air, depending on the particular system at hand.
Referring to FIG. 5C, yet another design maintains the outer corners and edges 26 at a substantially 90 degree angle so as to substantially reduce the stagnation zone. However, the components 30 are made from thinner materials such that the walls 28 are thinner than usual (using FIG. 2 as a reference point, the thickness of these component walls would be something less than x). Despite being thinner, the corners and edges 26 of the components 30 are still thicker relative to the component walls 28, and experience has shown that these corners and edges 26 still create unacceptable localized hot spots.
Yet another approach is to chamfer the outer corner or edges 32 of the component as shown in FIG. 5D. This configuration allows for the corner/edge 32 to be made to an acceptable thickness. However, like the curved corner/edge 20 design in FIG. 5A, the chamfered corner/edge 32 design departs from the 90 degree sharp corner configuration and, therefore, flow stagnation remains a concern.
None of the previously designs have successfully addressed both problems of flow stagnation and the undesirable heat concentrations that can occur at corners and/or edges of components exposed to high temperature flow environments. Thus, one object according to aspects of the present invention is to provide a system for such components that not only provides enhanced heat distribution properties at corner and/or edges regions but also avoids the problem of stagnant flow. These and other objects according to aspects of the present invention are addressed below.